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The Anatomy of Sea Turtles
Jeanette Wyneken, Ph.D.
Illustrated by Dawn Witherington
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LUNG and AIRWAY ANATOMY
Lungs and Airways
The pulmonary system is composed of the
glottis, trachea, a bronchus to each lung, and the
left and right lungs. The airways begin at the
glottis, which is located in the middle to posterior
portion of the tongue (Fig 160). The glottis and its
muscles are supported ventrally by the hyoid
apparatus. The glottis opens during air passage
and is closed during breath-holding. The glottis
leads directly into the trachea, which is supported
by complete cartilaginous rings that are usually
white, except in decomposing animals or some
turtles with pulmonary disease. The trachea is long
and bifurcates into two bronchi dorsal and anterior
to the heart. These then enter the anterior part of the
lungs next to the pulmonary arteries. The bifurcation
begins internally, anterior to the external division to
form the bronchi. The bronchi extend for virtually the
length of the lungs and have many openings into the
complex internal lobes of the lungs (Fig. 161). Unlike
the bronchi of mammalian lungs, these openings
lead to chambers that are not supported by cartilage.
There are no secondary bronchi in sea turtles.
brain
tongue
{
olfactory
sac
mouth
hyoid
glottis
trachea
Fig. 160. Parasagittal section of a hawksbill showing the airway. The hyoid apparatus,
including both bony and cartilaginous portions, supports the glottis ventrally. The glottis,
located between the hyoid and the surface of the tongue, is closed in this dissection.The
large tracheal diameter is maintained by cartilaginous rings. The trachea is lined by
smooth epithelium.
The Anatomy of Sea Turtles
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LUNG and AIRWAY ANATOMY
Fig. 161. Longitudinal section through a loggerhead bronchus. The lungs of
cheloniids are spongy in construction and red in color. They also have a large
surface area but are not as densely constructed as the lungs of leatherbacks.
The large-bore trachea has many openings to the chambers of the lung along
its length. These openings are not supported by cartilage once they leave the
bronchus. The unsupported airways extend to the air exchange surfaces called
faveoli and ascini. The trachea and bronchus are supported by cartilage, which
resists collapse during ventilation and diving.
The lungs are located dorsally and are attached
dorsally to the carapace and vertebral column. In
some species, (e.g., L. kempii and C. caretta) the
lungs are more closely attached to the vertebral
column than in other species. Ventrally, the left
lung is attached to the stomach via the
gastropulmonary ligament. The right lung is
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attached to the right lobe of the liver by the
hepatopulmonary ligament. Posteriorly, the
lungs attach to the peritoneum that overlies the
kidneys and adrenal glands and are adjacent to the
gonads. The medial border of each lung is firmly
attached (Fig. 162) via fibrous connections to
dorsolateral surfaces of the vertebral column.
The Anatomy of Sea Turtles
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LUNG and AIRWAY ANATOMY
Fig. 162. CT scan showing the lungs in a Kemp's
ridley. This CT shows the position, form, and the
extent of the lungs and airways in a living Kemp's
ridley turtle. The medial surfaces of the lungs are
attached tightly to the vertebral column.
All sea turtles have multichambered lungs (there
are multiple lobes contained within the body of the
lung). The lobes are not obvious externally. The
by movements of ventral muscles of the pelvic and
pectoral girdles that attach to the plastron,
compression of the inguinal region, and rocking of
Fig. 163. Longitudinal section
through a leatherback lung. The
lungs of leatherbacks are
characterized by more dense
construction. The high surface
area, dense parenchyma, high
levels of connective tissue, and
extensive blood supply make
leatherback lungs particularly
spongy and deep red in color.
lung tissue is spongy and highly elastic (Figs. 161
and 163) in sea turtles.
Ventilation of the lungs occurs without the
assistance of a diaphragm. Marine turtles ventilate
the shoulder muscle masses to change the pressure
within the pleuroperitoneal cavity. Sea turtles
have a large tidal volume. Under normal
circumstances, they breath-hold until blood
oxygen levels drop to low levels.
The Anatomy of Sea Turtles
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